LU85432A1 - PROCESS FOR THE SURFACE TREATMENT OF A STEEL SHEET - Google Patents
PROCESS FOR THE SURFACE TREATMENT OF A STEEL SHEET Download PDFInfo
- Publication number
- LU85432A1 LU85432A1 LU85432A LU85432A LU85432A1 LU 85432 A1 LU85432 A1 LU 85432A1 LU 85432 A LU85432 A LU 85432A LU 85432 A LU85432 A LU 85432A LU 85432 A1 LU85432 A1 LU 85432A1
- Authority
- LU
- Luxembourg
- Prior art keywords
- sheet
- aqueous solution
- potential difference
- surface treatment
- steel sheet
- Prior art date
Links
- 238000000034 method Methods 0.000 title claims description 14
- 238000004381 surface treatment Methods 0.000 title claims description 4
- BDAGIHXWWSANSR-UHFFFAOYSA-N methanoic acid Natural products OC=O BDAGIHXWWSANSR-UHFFFAOYSA-N 0.000 claims description 10
- 239000007864 aqueous solution Substances 0.000 claims description 9
- 229910000831 Steel Inorganic materials 0.000 claims description 7
- 238000005554 pickling Methods 0.000 claims description 7
- 239000000243 solution Substances 0.000 claims description 7
- 239000010959 steel Substances 0.000 claims description 7
- OSWFIVFLDKOXQC-UHFFFAOYSA-N 4-(3-methoxyphenyl)aniline Chemical compound COC1=CC=CC(C=2C=CC(N)=CC=2)=C1 OSWFIVFLDKOXQC-UHFFFAOYSA-N 0.000 claims description 5
- 235000019253 formic acid Nutrition 0.000 claims description 5
- WPYMKLBDIGXBTP-UHFFFAOYSA-N benzoic acid Chemical compound OC(=O)C1=CC=CC=C1 WPYMKLBDIGXBTP-UHFFFAOYSA-N 0.000 claims description 4
- 150000007524 organic acids Chemical class 0.000 claims description 3
- 239000005711 Benzoic acid Substances 0.000 claims description 2
- 235000010233 benzoic acid Nutrition 0.000 claims description 2
- 239000003112 inhibitor Substances 0.000 claims description 2
- 239000002253 acid Substances 0.000 description 5
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 4
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 3
- 239000010410 layer Substances 0.000 description 3
- 150000007513 acids Chemical class 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- 230000001133 acceleration Effects 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 150000001805 chlorine compounds Chemical class 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N iron oxide Inorganic materials [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 1
- 235000013980 iron oxide Nutrition 0.000 description 1
- VBMVTYDPPZVILR-UHFFFAOYSA-N iron(2+);oxygen(2-) Chemical class [O-2].[Fe+2] VBMVTYDPPZVILR-UHFFFAOYSA-N 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 230000003472 neutralizing effect Effects 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 235000021110 pickles Nutrition 0.000 description 1
- 238000003672 processing method Methods 0.000 description 1
- 239000011241 protective layer Substances 0.000 description 1
- 150000003467 sulfuric acid derivatives Chemical class 0.000 description 1
- 229910021653 sulphate ion Inorganic materials 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25F—PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
- C25F1/00—Electrolytic cleaning, degreasing, pickling or descaling
- C25F1/02—Pickling; Descaling
- C25F1/04—Pickling; Descaling in solution
- C25F1/06—Iron or steel
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
- Chemical Treatment Of Metals (AREA)
Description
fri Λ l C 2311/8406.fri Λ l C 2311/8406.
CENTRE DE RECHERCHES METALLURGIQUES -CENTRUM V00R RESEARCH IN DE METALLURGIE,METALLURGICAL RESEARCH CENTER -CENTRUM V00R RESEARCH IN DE METALLURGIE,
Association sans but lucratif -Vereniging zonder winstoogmerk à BRUXELLES, (Belgique).Non-profit association -Vereniging zonder winstoogmerk in BRUXELLES, (Belgium).
: Procédé pour le traitement superficiel d'une tôle en acier.: Process for the surface treatment of a steel sheet.
I ' --- — — 1I '--- - - 1
La présente invention concerne un procédé pour le traitement superficiel d'une tôle en acier.The present invention relates to a method for the surface treatment of a steel sheet.
On sait que dans les processus de fabrication, tant à chaud qu' à froid, la tôle d'acier se couvre généralement d'une couche d'oxydes plus ou moins épaisse qu'il est le plus souvent nécessaire d'éliminer avant l'utilisation ultérieure de la tôle.It is known that in the manufacturing processes, both hot and cold, the steel sheet is generally covered with a more or less thick layer of oxides which it is most often necessary to remove before the subsequent use of the sheet.
Les méthodes classiques d'élimination de cette couche d'oxydes consistent à décaper les surfaces au moyen d'une solution a-queuse d'un acide minéral tel que l’acide sulfurique ou l'acide chlorhydrique. Le caractère agressif de ces acides à l'égard de l'acier impose de neutraliser ces acides et ensuite de rincer soigneusement les tôles après décapage, afin d'éliminer de leur surface toute trace de sulfate ou de chlorure. Après rinçage, les tôles doivent encore être immédiatement revêtues d'une couche protectrice, généralement un film d'huile.Conventional methods of removing this layer of oxides consist of pickling the surfaces with an aqueous solution of a mineral acid such as sulfuric acid or hydrochloric acid. The aggressive nature of these acids with regard to steel makes it necessary to neutralize these acids and then to rinse the sheets carefully after pickling, in order to remove from their surface any trace of sulphate or chloride. After rinsing, the sheets should still be immediately coated with a protective layer, usually an oil film.
- 2 - afin de prévenir toute oxydation de leur surface par l'atmosphère.- 2 - in order to prevent any oxidation of their surface by the atmosphere.
Ces méthodes exigent donc une série d'opérations qui prennent du temps et qui consomment des quantités non négligeables de * réactifs chimiques de neutralisation.These methods therefore require a series of operations which take time and which consume significant quantities of chemical neutralizing reagents.
V*V *
En outre, l'opération de rinçage conduit à déverser dans l’environnement d'importantes quantités de sulfates ou de chlorures, qu'il n'est pas possible d'éliminer de façon économique.In addition, the rinsing operation results in the discharge into the environment of large quantities of sulfates or chlorides, which cannot be eliminated economically.
Outre leur aspect économique qui n'est pas très favorable, ces méthodes de décapage à l'acide sulfurique ou chlorhydrique posent donc un problème de protection du milieu naturel.Besides their economic aspect which is not very favorable, these methods of pickling with sulfuric or hydrochloric acid therefore pose a problem of protection of the natural environment.
Pour remédier à ces inconvénients sérieux, le présent deman-deur a proposé antérieurement de pratiquer le décapage des tôles d'acier au moyen d'une solution d'un acide organique, en particulier de l'acide formique. Cet acide est particulièrement avantageux car son prix n'est pas élevé, il ne forme pas à la surface de la tôle des composés agressifs à l'égard de l'acier et il peut être aisément oxydé en CC^ et ^O, ce qui permet son rejet sans danger pour l'environnement.To remedy these serious drawbacks, the present applicant has previously proposed to pickle steel sheets using a solution of an organic acid, in particular formic acid. This acid is particularly advantageous because its price is not high, it does not form on the surface of the sheet compounds which are aggressive towards steel and it can be easily oxidized to CC ^ and ^ O, which allows its release without danger to the environment.
ί !ί!
Il est cependant apparu que cet acide présentait une cinétique de réaction relativement faible à l'égard de certains oxydes présents à la surface des tôles; il en résulte une durée de traitement relativement longue qui, dans les procédés de traitement continus, limite la vitesse de défilement de la tôle et la productivité de la ligne de traitement.However, it appeared that this acid exhibited relatively low reaction kinetics with respect to certain oxides present on the surface of the sheets; this results in a relatively long processing time which, in continuous processing methods, limits the speed of movement of the sheet and the productivity of the processing line.
1%1%
La présente invention a pour objet un procédé permettant de * remédier à cet inconvénient.The present invention relates to a method making it possible to * remedy this drawback.
! À ψ * - 3 -! AT ψ * - 3 -
Le procédé qui fait l'objet de la présente invention, dans lequel on met la tôle, couverte d'une couche d'oxydes, en contact avec une solution aqueuse d'au moins un acide organique, de préférence l'acide formique, est essentiellement caractérisé en ce qu'au sein de la dite solution on crée une différence de po-tentiel entre la dite tôle et au moins une électrode auxiliaire, de préférence une électrode inerte.The process which is the subject of the present invention, in which the sheet metal, covered with a layer of oxides, is brought into contact with an aqueous solution of at least one organic acid, preferably formic acid, is essentially characterized in that within said solution a po-tential difference is created between said sheet and at least one auxiliary electrode, preferably an inert electrode.
• Par électrode inerte on entend une électrode qui ne réagit pas avec la solution aqueuse.• By inert electrode is meant an electrode which does not react with the aqueous solution.
Selon une variante intéressante du procédé de l'invention, on établit la dite différence de potentiel en reliant la tôle au pôle négatif et la ou les électrode(s) auxiliaire(s) au pôle positif d'une source de courant continu.According to an advantageous variant of the method of the invention, the said potential difference is established by connecting the sheet to the negative pole and the auxiliary electrode (s) to the positive pole of a direct current source.
Dans le cadre de cette variante, la dite différence de potentiel est avantageusement choisie entre O et 10 volts.In the context of this variant, the said potential difference is advantageously chosen between 0 and 10 volts.
On a en effet constaté qu'une différence de potentiel faible, de l'ordre de 1 ou 2 volts, provoquait déjà une augmentation de la cinétique de réaction, mais que l'on n’obtenait plus d' accélération supplémentaire au-delà d'environ 10 volts.It has indeed been observed that a small potential difference, of the order of 1 or 2 volts, already causes an increase in the reaction kinetics, but that no further acceleration is obtained beyond 'about 10 volts.
Egalement selon l'invention, la dite solution aqueuse contient au maximum 720 gr d'acide formique par litre de solution; cette valeur correspond au point azéotrope de la solution.Also according to the invention, said aqueous solution contains a maximum of 720 gr of formic acid per liter of solution; this value corresponds to the azeotropic point of the solution.
Toujours selon l'invention, la solution aqueuse peut, de façon· connue en soi, contenir au moins un inhibiteur de décapage, tel que l'acide benzoïque ou un de ses dérivés.Still according to the invention, the aqueous solution may, in a manner known per se, contain at least one pickling inhibitor, such as benzoic acid or one of its derivatives.
Selon la présente invention, on peut faire passer la tôle entre deux électrodes auxiliaires immergées dans la dite solution aqueuse, de façon à accélérer la réaction de décapage sur les à ► » - 4 - deux faces de la tôle simultanément.According to the present invention, the sheet can be passed between two auxiliary electrodes immersed in said aqueous solution, so as to accelerate the pickling reaction on the two sides of the sheet simultaneously.
Il ne sortirait cependant pas du cadre de l'invention de faire défiler la tôle devant une électrode auxiliaire, de façon à ne ^ décaper qu'une seule face de la tôle. Cette dernière mise en oeuvre s'avère particulièrement intéressante lorsque la tôle doit subir ultérieurement un autre traitement, par exemple de recouvrement par galvanisation, sur une seule face.It would not, however, depart from the scope of the invention to scroll the sheet in front of an auxiliary electrode, so as to scour only one side of the sheet. This latter implementation is particularly advantageous when the sheet must subsequently undergo another treatment, for example covering by galvanization, on one side.
Parmi les avantages que procure le procédé de l'invention, on peut citer : - une diminution du temps de décapage, se traduisant par une augmentation de la vitesse de défilement de la tôle et/ou par une diminution de longueur ou de profondeur de l'installation de traitement; - l'absence de pollution de l'environnement; ~ - la possibilité de traiter une seule face ou les deux faces d'une tôle; - la possibilité de produire des oxydes de fer de haute pureté par traitement chimigue simple des solutions; - le démarrage plus rapide des lignes de traitement.Among the advantages which the process of the invention provides, there may be mentioned: a reduction in the pickling time, resulting in an increase in the speed of travel of the sheet and / or in a reduction in length or depth of 'treatment facility; - the absence of environmental pollution; ~ - the possibility of treating a single face or both sides of a sheet; - the possibility of producing high purity iron oxides by simple chemical treatment of the solutions; - faster start-up of treatment lines.
/ -/ -
Claims (5)
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| LU85432A LU85432A1 (en) | 1984-06-26 | 1984-06-26 | PROCESS FOR THE SURFACE TREATMENT OF A STEEL SHEET |
| EP85870089A EP0169825A1 (en) | 1984-06-26 | 1985-06-19 | Process for the superficial treatment of steel plate |
| BE6/48102A BE902707A (en) | 1984-06-26 | 1985-06-19 | PROCESS FOR THE SURFACE TREATMENT OF A STEEL SHEET. |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| LU85432A LU85432A1 (en) | 1984-06-26 | 1984-06-26 | PROCESS FOR THE SURFACE TREATMENT OF A STEEL SHEET |
| LU85432 | 1984-06-26 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| LU85432A1 true LU85432A1 (en) | 1986-01-24 |
Family
ID=19730276
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| LU85432A LU85432A1 (en) | 1984-06-26 | 1984-06-26 | PROCESS FOR THE SURFACE TREATMENT OF A STEEL SHEET |
Country Status (3)
| Country | Link |
|---|---|
| EP (1) | EP0169825A1 (en) |
| BE (1) | BE902707A (en) |
| LU (1) | LU85432A1 (en) |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR1108926A (en) * | 1954-10-04 | 1956-01-19 | Renault | Electrolytic degreasing bath |
| US3420760A (en) * | 1965-04-30 | 1969-01-07 | Gen Dynamics Corp | Process for descaling steel strip in an aqueous organic chelating bath using alternating current |
| BE871631A (en) * | 1978-10-27 | 1979-04-27 | Centre Rech Metallurgique | PROCESS FOR CONTINUOUS PICKLING OF STEEL SHEETS. |
-
1984
- 1984-06-26 LU LU85432A patent/LU85432A1/en unknown
-
1985
- 1985-06-19 EP EP85870089A patent/EP0169825A1/en not_active Withdrawn
- 1985-06-19 BE BE6/48102A patent/BE902707A/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| EP0169825A1 (en) | 1986-01-29 |
| BE902707A (en) | 1985-12-19 |
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